With mixer on low, gently pour hot sugar syrup into gelatin mixture. Slowly increase speed to high; mix for about 10 minutes or until fluffy, stiff and shiny. Add food colouring; mix until marshmallow mixture is uniform orange colour, adding a few more drops if necessary to achieve desired shade.

Dust top with some of the remaining cornstarch. Flip pan upside down onto parchment paper–lined work surface. Carefully peel back parchment paper; dust top with remaining cornstarch mixture. Cut into squares. Store in airtight container for up to 3 days. (Note:Do not refrigerate.)